The global speciation continuum of the cyanobacterium <i>Microcoleus</i>

<b>Abstract:</b>Speciation is a continuous process driven by genetic, geographic, and ecological barriers to gene flow. It is widely investigated in multicellular eukaryotes, yet we are only beginning to comprehend the relative importance of mechanisms driving the emergence of barriers to gene flow in microbial populations. Here, we explored the diversification of the nearly ubiquitous soil cyanobacterium <i>Microcoleus</i>. Our dataset consisted of 291 genomes, of which 202 strains and eight herbarium specimens were sequenced for this study. We found that <i>Microcoleus vaginatus</i> represents a global speciation continuum of at least 12 lineages, which radiated during Eocene/Oligocene aridification and exhibit varying degrees of divergence and gene flow. The lineage divergence has been driven by selection, geographical distance, and the environment. Evidence of genetic divergence and selection was widespread across the genome, but we identified regions of exceptional differentiation containing candidate genes associated with stress response and biosynthesis of secondary metabolites.Alignments provided here were used in the paper "The global speciation continuum of the cyanobacterium <i>Microcoleus</i>" by Stanojković, A., Skoupý, S., Johannesson, H. &amp; Dvořák, P.**摘要：** 物种形成（Speciation）是由遗传、地理与生态障碍阻碍基因流的连续演化过程。该过程在多细胞真核生物中已得到广泛研究，但我们才刚刚开始理解驱动微生物种群中基因流（gene flow）障碍形成的各类机制的相对重要性。本研究针对几乎遍布全球的土壤蓝细菌（Cyanobacterium）*Microcoleus*（微鞘藻属）的演化分化展开探究。本研究的数据集共包含291个基因组，其中202株菌株与8份标本馆馆藏标本为本研究测序所得。研究发现，鞘丝微鞘藻（*Microcoleus vaginatus*）构成了至少包含12个演化支的全球物种形成连续体，这些演化支在始新世/渐新世（Eocene/Oligocene）全球干旱化事件期间发生辐射演化，并呈现出不同程度的分化与基因流。演化支的分化受到选择作用、地理距离与环境因素的共同驱动。全基因组范围内广泛存在遗传分化与选择作用的证据，但本研究鉴定出若干异常分化的基因组区域，其中包含与应激响应（stress response）及次生代谢产物（secondary metabolites）生物合成相关的候选基因。本数据集提供的序列联配（alignments）结果已应用于Stanojković A、Skoupý S、Johannesson H与Dvořák P发表的题为《蓝细菌微鞘藻属的全球物种形成连续体》的论文中。